SWITCHING MODE POWER SUPPLY, APPARATUS AND METHOD OF SUPPLYING POWER BY USING THE SAME, AND IMAGE FORMING APPARATUS THEREFOR

• US 20130114313A1
• Filed: 08/03/2012
• Published: 05/09/2013
• Est. Priority Date: 11/07/2011
• Status: Active Grant

• Current Assignee: HP Printing Korea Co., Ltd. (HP Inc.)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: JUNG, Hong-ki
• Granted Patent: US 9,397,553 B2
• Time in Patent Office: Days
• US Class Current: 363/49
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

A switching mode power supply (SMPS) usable with an image forming apparatus receives an alternating current (AC) power from an external electric power supply source and outputs a direct current (DC) power. When a supply state of an electric power to the image forming apparatus is turned off, electric charges charged in a capacitor of the SMPS are discharged.

Claims

1. A switching mode power supply (SMPS) usable with an image forming apparatus to receive an alternating current (AC) power from an external electric power supply source and to output a direct current (DC) power, the SMPS comprising:

a transformer to transform an electric power input to a primary coil and to output the transformed electric power to a secondary coil;

a switching unit connected to the primary coil to adjust the output power of the transformer; and

a blocking unit to block an electric power input to the switching unit according to a supply state of an electric power to the image forming apparatus.

2. The SMPS of claim 1, wherein the blocking unit blocks the electric power input to the switching unit when the supply state of the electric power to the image forming apparatus is a turned-off state.

3. The SMPS of claim 1, wherein the blocking unit comprises:

a signal detector to detect the supply state of the electric power to the image forming apparatus; and

an electric power blocking unit to block the electric power input to the switching unit according to the detected supply state.

4. The SMPS of claim 3, wherein the signal detector detects the supply state by sensing the AC power input from the external electric power supply source.

5. The SMPS of claim 3, wherein the signal detector detects the supply state by sensing a zero cross signal generated in the image forming apparatus.

6. The SMPS of claim 3, wherein:

the electric power blocking unit comprises a discharging circuit located between an electric power supplying terminal to supply the electric power input to the switching unit and the switching unit to discharge electric charges that are charged in the electric power supplying terminal; and

the electric power blocking unit blocks the electric power input to the switching unit by discharging the electric charges of the electric power supplying terminal when the supply state of the electric power to the image forming apparatus is the turned-off state.

7. The SMPS of claim 3, wherein the electric power blocking unit comprises a switching circuit to open and close a connection between an electric power supplying terminal to supply the electric power input to the switching unit and the switching unit, and the electric power blocking unit blocks the electric power input to the switching unit by opening the switching circuit when the supply state of the electric power to the image forming apparatus is the turned-off state.

8. The SMPS of claim 1, wherein the switching unit comprises:

a main switch connected to the primary coil to control the output power of the transformer; and

a switch controller to control a switching operation of the main switch.

9. A method of supplying an electric power of a switching mode power supply (SMPS) in an image forming apparatus, the method comprising:

transforming an electric power using a transformer of an SMPS;

determining a supply state of the electric power to an image forming apparatus; and

blocking the electric power input to a switching unit that adjusts an output of the electric power according to the determined supply state of the electric power to the image forming apparatus.

10. The method of claim 9, wherein the blocking of the electric power input to the switching unit comprises blocking the electric power when the determined supply state of the electric power to the image forming apparatus is a turned-off state.

11. The method of claim 9, wherein the determining of the supply state comprises sensing an alternating current (AC) power input from an external electric power supply source.

12. The method of claim 9, wherein the determining of the supply state comprises sensing a zero cross signal generated in the image forming apparatus.

13. The method of claim 9, wherein the blocking of the electric power input to the switching unit comprises discharging electric charges that are charged in an electric power supplying terminal that supplies the electric power input to the switching unit, when the supply state of the electric power to the image forming apparatus is a turned-off state.

14. The method of claim 9, wherein the blocking of the electric power input to the switching unit comprises opening a switching circuit that opens/closes connection between an electric power supplying terminal that supplies the electric power input to the switching unit and the switching unit, when the supply state of the electric power to the image forming apparatus is a turned-off state.

15. An image forming apparatus comprising:

an image forming unit to perform an image on a printing medium; and

a switching mode power supply (SMPS) to receive an alternating current (AC) power from an external electric power supply source and to output a direct current (DC) power to the image forming unit,

wherein the SMPS comprises;

a transformer to transform an electric power input to a primary coil and to output the transformed electric power to a secondary coil;

a switching unit connected to the primary coil to adjust the output power of the transformer; and

a blocking unit to block an electric power input to the switching unit based on a supply state of an electric power to the image forming apparatus.

16. The image forming apparatus of claim 15, wherein the blocking unit comprises:

a signal detector to detect the supply state of the electric power to the image forming apparatus; and

an electric power blocking unit to block the electric power input to the switching unit according to the detected supply state.

17. A switching mode power supply (SMPS) usable with an image forming apparatus to receive an alternating current (AC) power from an external electric power supply source and to output a direct current (DC) power, the SMPS comprising:

a transformer having a primary coil and a secondary coil to generate a driving voltage;

a switching unit configured to receive the driving voltage and to perform a switching operation on the primary coil according to the received driving voltage; and

a blocking unit configured to block the driving voltage from the switching unit according to a supply state of an electric power of the image forming apparatus.

18. The SMPS of claim 17, wherein the secondary coil comprises a sub-secondary coil to generate one or more output voltages usable in one or more components of the image forming apparatus, and an auxiliary coil to generate the driving voltage usable in the switching unit.

19. The SMPS of claim 17, wherein the blocking unit is disposed between the switching unit and the secondary coil to transmit the driving voltage from the secondary coil to the switching unit and to disconnect the driving voltage from the switching unit.

20. The SMPS of claim 17, wherein the blocking unit discharges a potential remaining on a passage from the secondary coil to the switching unit until the driving voltage is lower than a reset voltage of the image forming apparatus to correspond to a rebooting.

21. The SMPS of claim 17, wherein the blocking unit comprises a detector to detect the supply state from at least one of an input of the SMPS, an output of the SMPS, and a power on/off switch of one or more components of the image forming apparatus.